Biosecurity: Plugging the Holes

Creating biosecurity rules people won't follow wastes time and paper. Veterinarians are great at creating biosecurity protocols in great detail covering

John Waddell, DVM Sutton, NE | Jun 15, 2007

Creating biosecurity rules people won't follow wastes time and paper.

Veterinarians are great at creating “biosecurity protocols” in great detail covering the entire risk spectrum. However, the creation of standard operating protocols (SOPs) is the simple portion of biosecurity. The difficult part is getting the people who care for pigs to “buy in” and believe in the concepts. Without that belief, these SOPs are merely words on a page and a waste of paper.

Please do not misunderstand. Detailed protocols and procedures are a necessary part of any biosecurity plan and are always well-intentioned to keep disease out by many different means. However, unless the entire team believes in the concept of biosecurity, the protocols are doomed to failure.

A disease outbreak is seldom expected. In many situations, the point of entry and source of the disease introduction are never determined with 100% certainty.

It is actually the uncertainty of knowing that makes disease breaks so frustrating: “If it got in, and we don't know how it got in, then how do we prevent it from coming in again?”

I have often used the analogy of the rowboat to explain the value of a biosecurity program. Imagine yourself in a rowboat out in the middle of the lake. Now imagine that the bottom of the rowboat suddenly springs two dozen leaks. Some of these leaks are small, but some are very large. You first think about bailing the water out of the boat so that you won't sink. Then you realize that some of the holes are so large that you can never bail fast enough to prevent sinking. The only alternative is to start plugging all the holes!

First, you plug the largest holes, then bail a little more, then plug the medium-sized holes, bail a little more and then start plugging the small holes. Regardless of the size of the hole, as long as the water is coming in faster than you are bailing, you are still sinking!

Using the rowboat analogy with biosecurity, we must close the big holes (such as live animal introductions) first, then consider all of the small holes (people movement, supply introduction, etc.).

Case Study No. 1

A weaned pig producer had been purchasing select-age gilts from a multiplier farm that had been naïve for porcine reproductive and respiratory syndrome (PRRS) for several years. The producer had become complacent with the isolation procedures that he once was very disciplined about.

Instead of the planned 30-day isolation period, coupled with routine testing prior to entry, the immediate needs for gilts to fill a breeding group dictated that they move this load of gilts directly into the breeding barn.

Unbeknownst to the producer, the multiplier herd had been infected with the PRRS virus via aerosol from a neighboring herd. Even though the multiplier herd was following a routine testing protocol, the timing of the break was such that the group of gilts they delivered to the client had just turned positive and were missed by the testing protocol. The recipient herd soon broke with the PRRS virus.

This first case represents a biosecurity breach of the worst kind. It was a very large hole in the boat that should have been easily recognized and closed, but instead it sank the ship!

Case Study No. 2

A new boar stud was sited in a fairly hog dense, but PRRS-naïve area. It operated as a PRRS-naïve stud with a very high level of biosecurity. The boar stud employed all of the biosecurity tools that were available at the time. The long list included perimeter fencing, extended downtime, boar housing that was separate from the lab, supply quarantine, incoming animal isolation and testing.

Unfortunately, this was before the advent of air filtration technology in the swine industry, and actually before aerosol transmission of the PRRS virus was totally accepted as possible or probable.

Chances were fairly good that the PRRS-naïve neighboring herds would become positive and in late winter they did. Within weeks of the neighboring herd becoming PRRS positive, the same virus (as determined by genetic sequencing) found its way into the boar stud. Happily, the disease break was discovered almost immediately via serum testing and the stud was closed. No PRRS virus-contaminated semen was ever sent to client herds because of the quick actions of the attending veterinarian.

Had the air filtration technology been known and implemented at the time of the neighboring herd break, it is likely that this boar stud would have never been infected.